Deck 28: Information Decoding: Translation and Post-Translational Protein Processing

Question 1

What is the energy requirement for the formation of the 70S initiation complex?

A)1 GTP
B)1 ATP
C)1 GTP and 1 ATP
D)2 GTP (from hydrolysis of 1 GTP to GMP)
E)2 ATP (from hydrolysis of 1 ATP to AMP)

Answer 1

A

Question 2

Which of the bases present on the ribosome participates in the peptidyltransferase reaction?

A)A
B)C
C)G
D)T
E)U

Answer 2

A

Question 3

Which position of the anticodon is called the wobble base and with which base of the codon does it pair?

A)the 3' anticodon base which pairs with the first base of the codon
B)the 3' anticodon base which pairs with the last base of the codon
C)the middle anticodon base which pairs with the middle base of the codon
D)the 5' anticodon base which pairs with the first base of the codon
E)the 5' anticodon base which pairs with the last base of the codon

Answer 3

the 5' anticodon base which pairs with the last base of the codon

Question 4

In an E. coli cell, which of the following is the last item to be added to the 70S initiation complex?

A)mRNA
B)tRNA carrying formylmethionine
C)30S ribosomal subunit
D)50S ribosomal subunit
E)initiation factors IF1, IF2 and IF3

Question 5

What mRNA modification, just 5'to the start codon, is used by the eukaryotic cell to enable location of the first AUG codon?

A)a sequence of UAUAUA
B)a short sequence that forms a hairpin loop
C)a GC "box" that is recognized by eIFI
D)a string of four to five O-methylguanine residues
E)7-methylguanine cap on the 5' end of the mRNA

Question 6

In most cases, the first codon in prokaryotic mRNA codes for ________ while the first codon in eukaryotic mRNA codes for ________.

A)methionine; N-formylmethionine
B)N-formylmethionine; methionine
C)proline; N-formylproline
D)N-formylproline; proline
E)none of the above

Question 7

What enzyme attaches the correct amino acid to its tRNA?

A)aminoacyl-tRNA synthase
B)aminoacyl-tRNA synthetase
C)aminoacyl-tRNA transferase
D)aminoacyl-tRNA ligase
E)none of the above

Question 8

Which of the following is a difference between prokaryotic and eukaryotic translation?

A)the genetic code is different
B)prokaryotic ribosomes are free in the cytosol; eukaryotic chromosomes are always membrane bound
C)eukaryotic translation requires more protein factors
D)the ribosomes in prokaryotes are larger
E)none of the above

Question 9

By saying that the genetic code is degenerate, what does this imply?

A)the code is different for bacteria than for eukaryotes
B)some codons can code for non-standard amino acids
C)most amino acids have more than one codon
D)there is more than one start codon
E)there is more than one stop codon

Question 10

In a eukaryotic cell, what protein factor is responsible for delivering each aminoacyl-tRNA to the ribosome?

A)EF-Tu
B)EF-Ts
C)eEF1 $\alpha$
D)eEF1 $\beta$$\gamma$
E)eEF2

Question 11

Which are paired by a Shine-Dalgarno sequence?

A)the mRNA sequence just upstream from the start codon with the ribosome
B)the first codon of the mRNA with its tRNA
C)a termination codon with a release factor
D)the 30S subunit with the 50S subunit of the ribosome
E)none of the above

Question 12

What site is occupied by the tRNA^fMet during intitiation?

A)A site
B)P site
C)E site
D)binds first to A site then moves to P site
E)binds first to P site then moves to E site

Question 13

EF-Tu binds to ______ then to _______. This complex binds to the _____ site of the ribosome.

A)ATP; charged tRNA; P
B)GTP; charged tRNA; A
C)charged tRNA; ATP; A
D)charged tRNA; GTP; P
E)charged tRNA; GTP; A

Question 14

In prokaryotes, mRNA is ____________. In eukaryotes, mRNA is _____________.

A)equally monocistronic and polycistronic; mostly monocistronic
B)equally monocistronic and polycistronic; mostly polycistronic
C)mostly monocistronic; equally monocistronic and polycistronic
D)mostly polycistronic; equally monocistronic and polycistronic
E)mostly polycistronic; mostly monocistronic

Question 15

Which of the following explains how an aminoacyl-tRNA synthetase (AARS)recognizes the correct tRNA?

A)the AARS always recognizes the anticodon
B)the AARS always recognizes elements of the acceptor stem
C)the AARS always recognizes the size and sequence in the variable loop
D)the AARS always recognizes elements in the D loop and T _$\Psi$ C loop
E)the mechanism of AARS recognition varies from one enzyme to another

Question 16

In an E. coli cell, what protein factor is responsible for attaching the initiator tRNA?

A)IF2
B)eIF2
C)eIF2B
D)IF3
E)eIF5

Question 17

If a mutation in the template strand of DNA occurred in the following manner, which of the possible amino acid changes would occur? 5'-CAT-3' $\rarr$ 5'-TAT-3'

A)methionine $\rarr$ isoleucine
B)histidine $\rarr$ tyrosine
C)methionine $\rarr$ tyrosine
D)histidine $\rarr$ isoleucine
E)none of the above

Question 18

Which of the following is an intermediate in the reaction catalyzed by aminoacyl-tRNA synthetase?

A)pyrophosphorylated 3' hydroxyl on the tRNA
B)aminoacyl phosphate
C)aminoacyl pyrophosphate
D)aminoacyl adenylate
E)none of the above

Question 19

Which of the following correctly describes the formation of the peptide bond?

A)bond formation occurs while the tRNA in the P site moves to the E site, transferring the growing peptide chain to the tRNA that is moving from the A site to P site
B)the growing peptide is transferred first to the 30S subunit of the ribosome, then to the aminoacyl tRNA in the A site
C)bond formation occurs while transferring the growing peptide from the tRNA in the E site to the tRNA in the P site
D)bond formation occurs while transferring the growing peptide from the tRNA in the P site to the tRNA in the A site
E)none of the above

Question 20

A repetitive mRNA of GAG could produce which of the following?

A)polyglutamate
B)polyleucine
C)polyleucine, polyserine, or polyproline
D)polyarginine, polyglycine or polyglutamate
E)none of the above

Question 21

Prokaryotic proteins that are destined for secretion often contain a sequence of ________ amino acids at the ___ -terminus of the protein

A)hydrophilic; N
B)hydrophobic; N
C)hydrophilic; C
D)hydrophobic; C
E)none of the above

Question 22

How many ATP equivalents are required to make a protein of 150 amino acids?

A)150
B)300
C)450
D)600
E)none of the above

Question 23

During apoptosis, proteolysis is catalyzed by ______________ enzymes.

A)ubiquitin
B)autophagic lysosomal protease
C)phagocytic protease
D)HSP protease
E)caspase

Question 24

Show the first step (of the four-step process)for removal of the intein from the following:

Question 25

Translate the following mRNA into a peptide using the standard genetic code:
5'-AUGCGGAUCCAUGUACAACUGGACGCAGUACCGUAACGCGAU-3'

Question 26

What role do the Hsp70 proteins play in delivering proteins to their site of action such as the mitochondria?

A)aids in proper folding to allow protein to properly traverse membranes
B)prevents proteolysis of the unfolded protein
C)keeps the protein in an unfolded state to allow transfer across membranes
D)aids in formation of an intermediate folded protein that is present only during membrane transport
E)none of the above

Question 27

Proteins destined for extracellular transport produce an N-terminal signal sequence. What binds to this sequence for endoplasmic reticulum association?

A)signal recognition particle
B)ribosome receptor protein
C)Sec61 docking protein
D)SNARE protein
E)none of the above

Question 28

What is a polyribosome?

A)ribosomes that synthesize different subunits of the same protein
B)several ribosomes all attached to the same mRNA
C)ribosomes that are covalently bonded to each other in a polymer fashion
D)a ribosome that only produces proteins that will be excreted by the cell
E)none of the above